Biologically active neopeltolide compounds

ABSTRACT

The subject invention provides novel compositions of biologically active macrolide compounds which can advantageously be used in blocking cellular proliferation, treatment of cancer, treatment of fungal infections and control of spoilage of food, cosmetic and other consumer items.

CROSS-REFERENCE TO A RELATED APPLICATION

This application claims the benefit of U.S. provisional application Ser. No. 60/482,216, filed Jun. 23, 2003.

FIELD OF THE INVENTION

This invention relates to organic compounds and compositions which have useful therapeutic properties. More particularly, the invention concerns novel macrolide compounds having anti-proliferative, antitumor and antifungal activities; Pharmaceutical compositions comprising such compounds; and methods of their use for therapeutic purposes and in the control of spoilage of food, cosmetic and other consumer items.

BACKGROUND OF THE INVENTION

Of great importance to man is the control of pathological cellular proliferation such as that which occurs in the case of cancer. Considerable research and resources have been devoted to oncology and antitumor measures including chemotherapy. While certain methods and chemical compositions have been developed which aid in inhibiting, remitting, or controlling the growth of, for example, tumors, new methods and antitumor chemical compositions are needed. Anti-proliferative agents can also be useful in treating autoimmune diseases and inflammatory disease.

In searching for new biologically active compounds, it has been found that some natural products and organisms are potential sources for chemical molecules having useful biological activity of great diversity. For example, the diterpene commonly known as paclitaxel, isolated from several species of yew trees, is a mitotic spindle poison that stabilizes microtubules and inhibits their depolymerization to free tubulin (Fuchs, D. A., R. K. Johnson [1978] Cancer Treat. Rep. 62:1219–1222; Schiff, P. B., J. Fant, S. B. Horwitz [1979] Nature (London) 22:665–667). Paclitaxel is also known to have antitumor activity and has undergone a number of clinical trials which have shown it to be effective in the treatment of a wide range of cancers (Rowinski, E. K. R. C. Donehower [1995] N. Engl. J. Med. 332:1004–1014). See also, e.g., U.S. Pat. Nos. 5,157,049; 4,960,790; and 4,206,221.

Marine sponges have also proven to be a source of biologically active chemical molecules. A number of publications disclose organic compounds derived from marine sponges including Scheuer, P. J. (ed.) Marine Natural Products, Chemical and Biological Perspectives, Academic Press, New York, 1978–1983, Vol. I–V; Uemura, D., K. Takahashi, T. Yamamoto, C. Katayama, J. Tanaka, Y. Okumura, Y. Hirata (1985) J. Am. Chem. Soc. 107:4796–4798; Minale, L. et al. (1976) Fortschr. Chem. org. Naturst. 33:1–72 Faulkner, D. J., Nat. Prod. Reports 1984, 1, 251–551; ibid. 1987, 4, 539; ibid 1990, 7, 269; ibid 1993, 10, 497; ibid 1994, 11, 355; ibid 1995, 12, 22; ibid 1998, 15:113–58; ibid 2000 17:1–6; ibid 2000 17: 7–55; ibid 2001, 18: 1–49; 2002, 19: 1–48.; Gunasekera, S. P., M. Gunasekera, R. E. Longley and G. K. Schulte (1990) J. Org. Chem., 55:4912–4915.; Horton, P. A., F. E. Koehn, R. E. Longley, and O. J. McConnell, (1994) J. Am. Chem. Soc. 116: 6015–6016.

The success of chemotherapy for the treatment of various cancers can be substantially negated though cellular mechanisms which have evolved to enable neoplastic cells to subvert the cytotoxic effects of the drug. Some cells have developed mechanisms, which confer resistance to a number of structurally unrelated drugs. This multi-drug resistance (or MDR) phenomenon may arise through a number of different mechanisms. One of these involves the ability of a cell to reduce intracellular concentrations of a given drug through efflux from cytoplasm through and out the cell membrane by a series of unique ATP-dependent transporter proteins called-P-glycoproteins (Pgp) (Casazza, A. M. and C. R. Fairchild [1996] “Paclitaxel (Taxol®): mechanisms of resistance” Cancer Treat Res. 87:149–171). The surface membrane, 170 kDa Pgp, is encoded by the mdr-1 gene and appears to require substrate binding before transport begins. A wide range of compounds, including a number of structurally unrelated chemotherapeutic agents (adriamycin, vinblastine, colchicine, etoposide and Taxol), are capable of being transported by Pgp and render the cell resistant to the cytotoxic effects of these compounds. While many normal cell types possess Pgp, in general, tumor cell lines, which possess high levels of mRNA specific for Pgp, also exhibit overexpression of membrane Pgp and demonstrate resistance to various drugs. This intrinsic resistance can be increased multifold by incubation of cells with stepwise increasing doses of a particular drug over a period of several months. This can be further facilitated by the addition of the MDR reversal agent, verapamil (Casazza, A. M. and C. R. Fairchild [1996] supra) in combination with the particular drug. Drug resistant cell lines produced in this fashion exhibit resistance to drug cytotoxicity from 20 to 500 fold, compared to parental cell lines.

An additional target for cancer drug discovery is a high molecular weight membrane protein associated with multi-drug resistance properties of certain tumor cells known as the multidrug resistance-associated protein (MRP). MRP is a 190 kD membrane-bound glycoprotein (Bellamy, W. T. [1996], Annu. Rev. Pharmacol. Toxicol., 36: 161–183.) which belongs to the same family of proteins as the p-glycoprotein pump P-gp (Broxterman, H. J., Giaccone, G., and Lankelma, J. [1995], Current Opinion in Oncology, 7:532–540.) but shares less than 15% homology of amino acids with P-gp (Komorov, P. G., Shtil, A. A., Holian, O., Tee, L., Buckingham, L., Mechetner, E. B., Roninson, I. B., and Coon, J. S. [1998], Oncology Research, 10: 185–192.). MRP has been found to occur naturally in a number of normal tissues, including liver, adrenal, testis, and peripheral blood mononuclear cells (Krishan, A., Fitz, C. M., and Andritsch, I. [1997], Cytometry, 29: 279–285). MRP has also been identified in tissues of the lung, kidney, colon, thyroid, urinary bladder, stomach, spleen (Sugawara, I. [1998] The Cancer Journal, 8(2) and skeletal muscle (Kruh, G. D., Gaughan, K. T., Godwin, A., and Chan, A. [1995], Journal of the National Cancer Institute, 87(16): 1256–1258.). High levels of MRP have been implicated in multidrug resistance (MDR) in cancers of the lung and pancreas (Miller, D. W., Fontain, M., Kolar, C., and Lawson, T. [1996]. Cancer Letters, 107: 301–306.), and in neuroblastomas, leukemias and cancer of the thyroid (Kruh, G. D., Gaughan, K. T., Godwin, A., and Chan, A. [1995], Journal of the National Cancer Institute, 87(16): 1256–1258.), as well as bladder, ovarian and breast cancers (Barrand, M., Bagrij, T., and Neo, S. [1997]., General Pharmacology, 28(5): 639–645.). MRP-mediated MDR involves some of the same classes of compounds as those which are mediated by P-gp, including vinca alkaloids, epipodophyllotoxins, anthracyclins and actinomycin D (Barrand, M., Bagrij, T., and Neo, S. [1997]., General Pharmacology, 28(5): 639–645). However, the substrate specificity has been demonstrated to differ from that of P-gp (Komorov, P. G., Shtil, A. A., Holian, O., Tee, L., Buckingham, L., Mechetner, E. B., Roninson, I. B., and Coon, J. S. [1998], Oncology Research, 10: 185–192.). Drugs which would inhibit or which are not substrates for the MDR pump would, therefore, be useful as chemotherapeutic agents.

Of further significant importance to man is the control of fungi which can cause human, animal and plant diseases as well as food and product spoilage. Considerable research and resources have been devoted to identifying antifungal agents. While certain methods and chemical compositions have been developed that aid in inhibiting or controlling the growth of fungi, new methods and antifungal compositions are needed.

Human mycotic infections may be grouped into superficial, subcutaneous, and deep (or systemic) mycoses. Superficial fungal infections of skin, hair and nails may be chronic and resistant to treatment but rarely affect the general health of the patient. Deep mycoses, on the other hand, may produce systemic involvement and are sometimes fatal.

The deep mycoses are caused by organisms that live free in nature in soil or on decaying organic material and are frequently limited to certain geographic areas. In such areas, many people acquire the fungal infection. A majority develop only minor symptoms or none at all, and only a small minority of infections progress to full-blown serious or fatal disease. The host's cell-mediated immune reactions are of paramount importance in determining the outcome of such infections.

Post-harvest losses during storage of plant produce are caused, interalia, by fungal and bacterial pathogens. Fungicidal compounds have long been used to increase yields and extend agricultural production capabilities into new areas. They have also been extremely important tools for ameliorating season-to-season differences in yield and quality caused by weather-driven variations in disease pressure.

Chemical fungicides have provided an effective method of control; however, the public has become concerned about the amount of residual chemicals which might be found in food, ground water and the environment. Stringent new restrictions on the use of chemicals and the elimination of some effective pesticides from the market place could limit economical and effective options for controlling fingi.

One example of the need to control post-harvest spoilage of agriculture products pertains to green and blue molds of citrus fruits caused by Penicillium digitatum and P. italicum. These molds cause severe damage during storage and shipping. The existing fresh-market industry relies completely on a combination of several chemical treatments to deliver sound fruit to distant markets over substantial periods of time without excessive damage caused by these molds. Unfortunately, there are increasing concerns about the safety of the chemicals currently used to control these fungal pathogens. Also, there are increasing problems with fungal strains with resistance to the most effective compounds.

In another example, powdery mildew of grapes caused by Uncinula necator can cause severe damage even in dry areas such as California. Traditionally this disease was controlled with applications of elemental sulfur, but this necessitates frequent, high volume applications of an irritating material. The introduction of ergosterol biosynthesis inhibiting fungicides (primarily triazoles) greatly simplifies control, but also selects for tolerant strains. Some of these compounds are also known to have potential teratogenic effects and very long soil residuals. In these and other examples, alternative control methods are in great demand—particularly methods which are safer or more environmentally benign.

To prevent fungal spoilage it is common practice in many countries to spray produce with systemic fungicides in the field and to dip harvested produce in fungicide solutions prior to storage. Since the oncogenic nature of many of the most commonly used fungicides is increasingly recognized and because the persistence of most fungicides is increased by the low storage temperatures the postharvest use of fungicides is of growing concern.

Additionally, resistance to the fungicides, used has been reported and suppression of the main spoilage organism B. cinera by fungicides such as BENOMYL fungicide has been shown to result in increased population of A. brassicicola which causes a more penetrating rot of produce than B. cinera. See, for example, U.S. Pat. No. 5,869,038.

The future role of fungicides in agriculture is increasingly threatened by several factors including; the development of pest resistance, increasing concerns about food safety and environmental accumulation of toxic compounds. As older fungicides are removed from the market due to regulatory changes there is an increasing need to find new effective fungicidal compounds.

BRIEF SUMMARY OF THE INVENTION

The subject invention provides novel compositions of biologically active compounds that have utility for use in inhibiting cellular proliferation. In a specific embodiment, the compounds and compositions of the subject invention can be used in the treatment of cancer. In a second specific embodiment, the compounds and compositions of the subject invention can be used in the control of fungal growth.

In one embodiment, the novel compositions and methods of the subject invention can be used in the treatment of an animal hosting cancer cells including, for example, inhibiting the growth of tumor cells in a mammalian host. More particularly, the subject compounds can be used for inhibiting in a human the growth of tumor cells, including cells of breast, colon, CNS, ovarian, renal, prostate, liver, pancreatic, uterine, or lung tumors, as well as human leukemia or melanoma cells. The mechanisms for achieving anticancer activity exhibited by the subject compounds would lead a person of ordinary skill in the art to recognize the applicability of the subject compounds, compositions, and methods to additional types of cancer as described herein.

In accordance with the subject invention, methods for inhibiting cancer cells in a host include contacting tumor cells with an effective amount of the new pharmaceutical compositions of the invention. The cancer cells inhibited by the invention are those which are susceptible to the subject compounds described herein or compositions comprising those compounds.

In a further specific embodiment, the novel compositions and methods of the subject invention subject can be used in the control of fungal growth. Because of the biological activity of these compounds, they can be used for treatment of plant and animal fungal infections, to prevent spoilage of organic compositions such as food and cosmetics, and as disinfectants. In a preferred embodiment, the novel compounds, compositions and methods of use of the subject invention can advantageously be used to inhibit the growth of fungi in a mammalian host. As used herein, reference to “antifungal activity” includes fungicidal and fungistatic activity as well as the inhibition of fungal germination or growth.

In specific embodiments, the subject invention provides new macrolides, as exemplified by Neopeltolide (I).

Neopeltolide has not been isolated previously from a natural source nor has it been previously synthesized.

Additional aspects of the invention include the provision of methods for producing the new compounds and compositions.

Other objects and further scope of applicability of the present invention will become apparent from the detailed descriptions given herein; it should be understood, however, that the detailed descriptions, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent from such descriptions.

DETAILED DISCLOSURE OF THE INVENTION

The subject invention provides novel compositions of biologically active macrolide compounds which are useful for inhibiting pathological cellular proliferation.

Advantageously, the macrolide compounds of the subject invention can be used to inhibit unwanted cellular proliferation, including the pathogenic proliferation of tumor and fungal cells.

In a preferred embodiment, these compounds can be used for treating cancer. More specifically, the novel compounds, compositions and methods of use can advantageously be used to inhibit the growth of tumor and other cancer cells in a mammalian host. As described herein, the compounds of the subject invention have utility for use in the treatment of cancer. More particularly, the subject compounds can be used for inhibiting in a human the growth of tumor cells, including cells of breast, prostate, colon, CNS, ovarian, renal, liver, pancreatic, uterine, or lung tumors, as well as human leukemia or melanoma cells. The compounds also have utility in the treatment of multi-drug resistant cancer cells.

The subject invention further provides novel compositions of biologically active macrolide compounds which are useful in the control of fungal growth. Because of the biological activity of these compounds, they can be used for treatment of plant and animal fungal infections, to prevent spoilage of organic compositions such as food and cosmetics, and as disinfectants. In a preferred embodiment, the novel compounds, compositions and methods of use of the subject invention can advantageously be used to inhibit the growth of fungi in a mammalian host. As used herein, reference to “antifungal activity” includes fungicidal and fungistatic activity as well as the inhibition of fungal germination or growth.

In a preferred embodiment, the subject invention provides compounds having the following formula:

In a further specific embodiment, the subject invention provides compounds having the following formula

The subject invention further pertains to isolated enantiomeric compounds. The isolated enantiomeric forms of the compounds of the invention are substantially free from one another (i.e., in enantiomeric excess). In other words, the “R” forms of the compounds are substantially free from the “S” forms of the compounds and are, thus, in enantiomeric excess of the “S” forms. Conversely, “S” forms of the compounds are substantially free of “R” forms of the compounds and are, thus, in enantiomeric excess of the “R” forms. In one embodiment of the invention, the isolated enantiomeric compounds are at least about in 80% enantiomeric excess. In a preferred embodiment, the compounds are in at least about 90% enantiomeric excess. In a more preferred embodiment, the compounds are in at least about 95% enantiomeric excess. In an even more preferred embodiment, the compounds are in at least about 97.5% enantiomeric excess. In a most preferred embodiment, the compounds are in at least about 99% enantiomeric excess.

In accordance with the subject invention, methods for inhibiting cancer in a host include contacting cancer cells with an effective amount of the new pharmaceutical compositions of the invention. The tumor cells inhibited by the invention are those which are susceptible to the subject compounds described herein or compositions comprising those compounds.

The subject invention further provides methods of use of the new compounds and compositions of the invention, e.g., methods of inhibiting tumors and other cancer cells in an animal, preferably a mammal. Most preferably, the invention comprises a method for the antitumor treatment of a human in need of such treatment, i.e., a human hosting cancer cells, including breast, colon, liver, pancreatic, uterine, or lung tumor cells, or leukemia cells including multi-drug resistant cancer cells.

In preferred embodiments of the invention, the compounds are substantially pure, i.e., contain at least 95% of the compound as determined by established analytical methods.

In further preferred methods of the invention, salts and analogs within the scope of the invention are made by adding mineral acids, e.g., HCl, H₂SO₄, or strong organic acids, e.g., formic, oxalic, in appropriate amounts to form the acid addition salt of the parent compound or its derivative. Also, synthesis type reactions may be used pursuant to known procedures to add or modify various groups in the preferred compounds to produce other compounds within the scope of the invention.

As used in this application, the terms “analogs,” refers to compounds which are substantially the same as another compound but which may have been modified by, for example, adding or removing side groups.

The scope of the invention is not limited by the specific examples and suggested procedures and uses related herein since modifications can be made within such scope from the information provided by this specification to those skilled in the art.

A more complete understanding of the invention can be obtained by reference to the following specific examples of compounds, compositions, and methods of the invention. The following examples illustrate procedures for practicing the invention. These examples should not be construed as limiting. All percentages are by weight and all solvent mixture proportions are by volume unless otherwise noted. It will be apparent to those skilled in the art that the examples involve use of materials and reagents that are commercially available from known sources, e.g., chemical supply houses, so no details are given respecting them.

EXAMPLE 1 Isolation and Structure Elucidation of Neopeltolide (I)

A. Collection and Taxonomy of the Source Organism

A sample of a sponge identified as belonging to the Family Neopeltidae (Phylum: Porifera, Class Demospongiae, Order Lithistida, Family Neopeltidae) was collected using the Johnson Sea Link manned submersible at a depth of 433 m off the North Jamaican Coast (latitude 18 28.638′N, longitude 78 10.996′W). The sponge morphology is that of a plate with visible pores on the upper surface, stony in consistency, and white in color. A reference sample preserved in ethanol has been deposited in the Harbor Branch Oceanographic Museum (catalog number 003:01004, DBMR number 23-VIII-93-5-010) and is available for taxonomic evaluation by those skilled in the art.

B. Isolation and Structure Elucidation of Neopeltolide (I).

One hundred and five (105) grams of the frozen Neopeltidae sponge, 23-VIII-93-5-010 was extracted exhaustively by macerating with ethanol using a Waring Blender (5×250 mL). The combined filtered extracts were concentrated by distillation under reduced pressure to yield 3.2 g of crude residue. The residue was partitioned between n-butanol and water (3×50 ml portions). After concentration, the n-butanol phase (0.7 g) was chromatographed under vacuum column chromatographic conditions on an Kieselgel 60H (EM SCIENCE) stationary phase. A 150 mL Buchner funnel fitted with a medium porosity fritted glass disc was used as the column. The stationary phase was packed to a total height of 4 cm. The butanol partition was applied as a slurry to the column in a mixture of heptane-ethyl acetate (8:2 v/v).

Fractions were eluted using a 20% step gradient of ethyl acetate in heptane followed by a series of fractions containing increasing amounts of methanol in ethyl acetate [Fraction 1: heptane-ethyl acetate 80:20 v/v (150 ml); Fraction 2: heptane-ethyl acetate 60:40 v/v (150 ml); fraction 3: heptane-ethyl acetate 40:60 v/v (150 ml); Fraction 4: heptane-ethyl acetate 25:75 v/v (150 ml); Fraction 5: heptane-ethyl acetate 20:80 v/v (150 ml); Fraction 6: ethyl acetate (150 ml); Fraction 7: ethyl acetate-methanol 75:25 v/v (150 ml); Fraction 8: ethyl acetate-methanol 50:50 v/v (150 ml); Fraction 9 methanol (150 ml).

Neopeltolide eluted cleanly into Fraction 3. Fraction 3 was further separated by HPLC using a Vydac C-18 Protein and Peptide Column (10 mm×250 mm, 10μ particle size), flow rate=3 ml/min; eluent: water:acetonitrile 40:60 v/v; monitored by UV at 230 nm. Neopeltolide elutes after approximately 6.2 column volumes under these conditions.

Neopeltolide (I): colorless oil; MS: m/z observed 591.32692, calculated 591.32816 Δ=−1.2 mmu for formula C₃₁H₄₇O₉N₂ (M+H⁺); [α]²⁴ _(D)=+23.0 (c 0.0024 g/ml in methanol). See Table 1 for ¹H and ¹³C NMR data.

TABLE 1 NMR Data for Neopeltolide (I) Atom # ¹H (mult. J in Hz) ¹³C (mult)  1 — 172.5 (s)  2 A 2.66 (dd J = 14.8, 4.3)  43.0 (t) B 2.33 (dd J=14.5, 10.8)  3 4.09 (m)  70.6 (d)  4 A 1.84 (m)  35.9 (t) B 1.53 (m)  5 5.21 (m)  68.5 (d)  6 A 1.68 (m)  37.0 (t) B 1.54 (m)  7 3.58 (dd J=10.4, 9.8)  76.6 (d)  8 A 1.40 (m)  44.8 (t) B 1.29 (m)  9 1.45 (m)  32.0 (d) 10 A 1.58 (m)  42.9 (t) B 1.14 (m) 11 3.63 (m)  76.5 (d) 12 A 1.90 (m)  40.5 (t) B 1.39 (m) 13 5.18 (m)  73.8 (d) 14 A 1.75 (m) B 1.53 (m)  37.5 (t) 15 AB 1.39 (2H m)  19.6 (t) 16 0.93 (3H t J=7.3)  14.1 (q) 17 0.99 (3H d J=8.8)  25.9 (q) 11-OCH3 3.33 (3H s)  56.4 (q)  1′ — 166.4 (s)  2′ 5.91 (bd J=11.3) 121.3 (d)  3′ 6.35 (dt J=11.3, 7.45) 149.8 (d)  4′ AB 3.02 (2H q J=7.45)  28.4 (t)  5′ AB 2.73 (2H t J=7.45)  26.0 (t)  6′ — 141.5 (s)  7′ 7.55 (bs) 135.3 (d)  8′ — 161.3 (s)  9′ 6.26 (bd J=12.0) 115.8 (d) 10′ 6.05 (ddd J=12.0, 6.0, 6.0) 138.5 (d) 11′ AB 4.31 (2H bd J=4.9)  40.6 (t) 12′ 158.9 (s) 12′-OCH3 3.67 (3H s)  52.4 (q)

EXAMPLE 2 Antitumor Effects of Neopeltolide (I)

A. Effects of Neopeltolide on In Vitro Proliferation of Tumor Cell Lines

Neopeltolide was analyzed as to its effect on the proliferation of A549 human lung adenocarcinoma, NCI-ADR-RES (Formerly MCF-7/ADR) human breast cancer and P388 murine leukemia cell lines. P388 cells were obtained from Dr. R. Camalier, National Cancer Institute, Bethesda, Md., and A549 and NCI-ADR-RES cells were obtained from American Type Culture Collection, Rockville, Md.

All cell lines are maintained in Roswell Park Memorial Institute (RPMI) medium 1640 supplemented with 100 U/mL penicillin 100 μg/ml streptomycin, 60 μg/ml L-glutamine, 18 mM HEPES, 0.05 mg/mL gentamycin and 10% fetal bovine serum. Cell lines are cultured in plastic tissue culture flasks and kept in an incubator at 37° C. in humidified air containing 5% CO₂.

To assess the antiproliferative effects of agents against the various cell lines, 200 μl cultures (96-well tissue culture plates, Nunc, Denmark) are first established at 3×10⁴ cells/ml for adherent lines (A549, NCI ADR-RES) and 1×10⁵ for non-adherent lines (P388) in tissue culture medium and incubated for 24 hr at 37° C. in 10% CO₂ in air in order to allow cells to attach. A volume of 100 μl of medium is removed from each test well and 100 μl of medium containing serial, two-fold dilutions of the test agent is added to each well containing tumor cells. Medium without drug is also added to wells containing tumor cells which serve as no drug controls. Positive drug controls are included to monitor drug sensitivity of each of the cell lines. These include varying dilutions of 5-fluorouracil, doxorubicin.

After 72-h exposures (Adherent cell lines) or 48-hr exposure (Non-adherent cell lines), tumor cells are enumerated using 3-[4,5-Dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) (M. C. Alley, et al., Cancer Res. 48:589, 1988) as follows:

A volume of 75 μl of warm growth media containing 5 mg/ml MTT is added to each well, cultures returned to the incubator, and left undisturbed for 3 hours. To spectrophotometrically quantitate formation of reduced formazan, plates are centrifuged (900×g, 5 minutes), culture fluids removed by aspiration, and 200 μl of acidified isopropanol (2 ml concentrated HC/liter isopropanol) added per well. The absorbance of the resulting solutions is measured at 570 nm with a plate reader (Spectra II Tecan Laboratories).

The absorbance of tests wells is divided by the absorbance of drug-free wells, and the concentration of agent that results in 50% of the absorbance of untreated cultures (IC₅₀) is determined by linear regression of logit-transformed data (D. J. Finney, Statistical Method in Biological Assay, third ed., pp.316–348, Charles Griffin Co., London, 1978). A linear relationship between tumor cell number and formazan production has been routinely observed over the range of cell densities observed in these experiments.

The two standard drug controls (indicated above) are included in each assay to monitor the drug sensitivity of each of the cell lines and IC₅₀ values are determined for each drug-cell combination.

A summary of results in these assays for Neopelotide I can be found in Table 2.

TABLE 2 Cytotoxicity Results for Neopeltolide A549 NCIADR-RES P388 IC₅₀ IC₅₀ IC₅₀ Neopeltolide (I) 1.17 nM 5.1 nM 0.56 nM

EXAMPLE 3 Antifungal Activity of Neopeltolide (I)

A. Effects of Neopeltolide on In Vitro Growth of Candida albicans

The antifungal activity of neopeltolide against Candida albicans (American Type Culture Collection strain 44506) was determined through the use of both agar diffusion and broth dilution assays.

Agar diffusion assays were performed using Sabouraud Dextrose agar plates seeded with the test microbe at 10⁵/ml. Disks (6.35 mm, Schliecher and Schuell) were impregnated with 25 μg of neopeltolide, allowed to dry and then placed on the agar surface. After incubation at 37° C. for 24 hours the zones of growth inhibition were determined. A control disk containing 100 IU nystatin was run on the same plate as the neopeltolide: the zone of inhibition was 28 mm.

Broth dilution assays were performed as standard 96-well microtiter assays in a total volume of 50 μl with a seeding density of 10³ cells/ml. The concentration range for neopeltolide ranged from 5 to 0.4 μg/ml as two-fold dilutions. Plates were incubated at 37° C. for 24 hours at which time the Minimum Inhibitory Concentration (MIC) was determined as the lowest concentration in the test range that completely inhibited growth of C. albicans. 5-fluorocytosine was used as an antifungal control for the assay: the MIC for 5-fluorocytosine was 0.62 μg/ml.

Results: Neopeltolide I shows a growth inhibitory zone of 17 mm when tested at a concentration of 25 μg/disk in the C. albicans disk diffusion assay. The Minimum inhibitory concentration (MIC) of neopeltolide against C. albicans is 0.625 μg/ml.

EXAMPLE 4 Formulation and Administration

The compounds of the invention are useful for various non-therapeutic and therapeutic purposes. It is apparent from the testing that the compounds of the invention are effective for inhibiting cell growth. Because of the antiproliferative properties of the compounds, they are useful to prevent unwanted cell growth in a wide variety of settings including in vitro uses. They are also useful as standards and for teaching demonstrations. As disclosed herein, they are also useful prophylactically and therapeutically for treating cancer cells in animals and humans.

Therapeutic application of the new compounds and compositions containing them can be accomplished by any suitable therapeutic method and technique presently or prospectively known to those skilled in the art. Further, the compounds of the invention have use as starting materials or intermediates for the preparation of other useful compounds and compositions.

The dosage administration to a host in the above indications will be dependent upon the identity of the cancer cells, the type of host involved, its age, weight, health, kind of concurrent treatment, if any, frequency of treatment, and therapeutic ratio.

The compounds of the subject invention can be formulated according to known methods for preparing pharmaceutically useful compositions. Formulations are described in detail in a number of sources which are well known and readily available to those skilled in the art. For example, Remington's Pharmaceutical Science by E. W. Martin describes formulations which can be used in connection with the subject invention. In general, the compositions of the subject invention will be formulated such that an effective amount of the bioactive compound(s) is combined with a suitable carrier in order to facilitate effective administration of the composition.

In accordance with the invention, pharmaceutical compositions comprising, as an active ingredient, an effective amount of one or more of the new compounds and one or more non-toxic, pharmaceutically acceptable carrier or diluent. Examples of such carriers for use in the invention include ethanol, dimethyl sulfoxide, glycerol, silica, alumina, starch, and equivalent carriers and diluents.

To provide for the administration of such dosages for the desired therapeutic treatment, new pharmaceutical compositions of the invention will advantageously comprise between about 0.1% and 45%, and especially, 1 and 15%, by weight of the total of one or more of the new compounds based on the weight of the total composition including carrier or diluent. Illustratively, dosage levels of the administered active ingredients can be: intravenous, 0.01 to about 20 mg/kg; intraperitoneal, 0.01 to about 100 mg/kg; subcutaneous, 0.01 to about 100 mg/kg; intramuscular, 0.01 to about 100 mg/kg; orally 0.01 to about 200 mg/kg, and preferably about 1 to 100 mg/kg; intranasal instillation, 0.01 to about 20 mg/kg; and aerosol, 0.01 to about 20 mg/kg of animal (body) weight.

It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to persons skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims. 

1. A compound having the following structural formula:

or a salt thereof.
 2. The compound, according to claim 1, having the following formula:


3. A method for inhibiting cellular proliferation, said method comprising administering to a patient in need of such treatment an effective amount of a compound having the following structure:

or a salt of said compound.
 4. The method, according to claim 3, wherein said compound has the following structure:


5. The method, according to claim 3, wherein the cellular proliferation is associated with a condition selected from group consisting of autoimmune disorders, inflammation, tumors and cancer.
 6. The method, according to claim 5, wherein the cancer is selected from the group consisting of breast cancer, colon cancer, cancer, CNS cancer, liver cancer, lung cancer, leukemia, melanoma, ovarian cancer, uterine cancer, renal cancer, pancreatic cancer and prostate cancer.
 7. A pharmaceutical composition comprising a compound having the following structure:

or a salt of said compound, wherein said composition further comprises a pharmaceutically acceptable carrier.
 8. The pharmaceutical composition, according to claim 7, comprising a compound having the following structure:


9. A method for inhibiting fungal growth, said method comprising applying to a fungus a compound having the following structure:

or a salt of said compound.
 10. The method, according to claim 9, wherein said compound has the following structure:


11. The method, according to claim 9, used to inhibit the spoilage of food or cosmetics. 